High speed printers, optical character scanners and data display devices of several types have been developed and are in use. Most of these devices are dedicated to a particular application or system. In addition most of these devices are mechanical at least in part and suffer the limitations of mechanical devices as compared to electronic devices. Mechanical printers are reaching the upper limits of their effective speed because of their reciprocating action. The principal of hammering a symbol onto a medium has its limits in the laws of physics. It takes more energy to start and stop a mass hundreds of times per second no matter how small the mass than to start and stop a beam of light.
At present printers while reliable do not read check their output. If a defect such as a blot, a wood chip or a hole in the paper output medium caused the loss of a character the system would be unaware of such loss.
Optical character scanners in present use require that particular fonts be employed and that those fonts be recognized through extensive manipulation of the image and through extensive computer processing.
Data display devices in present use require many signals to be employed in transmitting symbols from the central processor to the display device. Actually the symbol is represented and stored in the central processor as a configuration of binary bits. Its output in graphic form requires a multiplicity of signals and computer instructions relating to its identity, its construction and its output position.
Some recent U.S. patents in the field of the invention are: 3,824,604 -- Stein, which discloses a solid state printing system employing a liquid crystal matrix to form characters. Unlike the present invention the system disclosed in said patent, considering the printer aspect of the present invention alone, uses a liquid crystal matrix to form the symbols and fiber optics to transmit the symbols, while the present invention uses liquid crystals to gate the symbol images and projects the images to the output medium. Other patents of interest are; U.S. Pat. No. 3,693,517 -- Clark, which discloses an electro mechanical printing device, U.S. Pat. No. 3,626,830 -- Sobottka, et. al., which discloses an electro mechanical printing device, and U.S. Pat. No. 3,499,112 -- Heilmeier, which discloses an electro optical display device which does not contemplate the same application as the present invention but does utilize liquid crystals in a manner suggestive of a television system. The patentee uses liquid crystals to modulate light as opposed to the gating of light. Also of interest are U.S. Pat. No. 3,453,648 -- Stegenga, which discloses a thermal printing device, and U.S. Pat. No. 3,354,817 -- Sakurai, et. al., which discloses a thermal printing device. 24